Apple black leather cases staining?

I received my iPhone 7+ last October, and purchased an Apple black leather case for it. Loved everything about it. I wear dress shirts for work each day, and keep the phone in the front pocket of the shirt, screen always facing my body; the phone protrudes above the edge of the pocket by roughly an inch. Yesterday my wife washed a load of my dress shirts and found a peculiar stain about an inch above the top of the pocket on each one, in the form of a dark, grainy line in the shape of the top of the phone. This morning I cleaned the case, and wore it in a dress shirt for about five hours, and saw a thin but noticeable line on the shirt corresponding to the position of the top of the phone. I searched the Apple Store and Google, but found no reference to this. Anyone seen/heard this?

I guess it's possible, though with a midnight blue I never noticed any of that. But I didn't wear it in a pocket like that (just pants pocket). Is it just along the edge of the case, meaning you put it in screen in/back out?

I guess it's possible, though with a midnight blue I never noticed any of that. But I didn't wear it in a pocket like that (just pants pocket). Is it just along the edge of the case, meaning you put it in screen in/back out?

I did take a couple of lens cleaner wipes to it (which I think were alcohol based), and when I firmly wiped the edges a black color cane on to the wipe. Perhaps the wrong thing to clean with, but at least I know there's no "grunge" on the top edge now

UPDATE: Unfortunately the case kept staining my shirts. If I recall correctly, This is the first truly black case they've made; perhaps something in the manufacturing process makes it so that after a certain point the dye begins to release from the leather. They probably never thought to test for that, especially most people don't carry their phones like I do, where the case is in constant contact with the fabric for hours. To bad, the case is very handsome and a pleasure to hold in the hand

UPDATE: Unfortunately the case kept staining my shirts. If I recall correctly, This is the first truly black case they've made; perhaps something in the manufacturing process makes it so that after a certain point the dye begins to release from the leather. They probably never thought to test for that, especially most people don't carry their phones like I do, where the case is in constant contact with the fabric for hours. To bad, the case is very handsome and a pleasure to hold in the hand

Well that stinks, at least for the black. I've known of others with black leather and not having that issue but I think most have it in their pants pocket rather than in a shirt. What color phone do you have? I wonder if a good leather sealer/treater would help keep the color in the case rather than on your shirts?? Couldn't hurt to try.